I'm running my gaming Linux from hard disk over USB3 which works perfectly. I made a bootable USB stick which boots directly to Steam "Big Picture" UI - works without problems as well.
^ that's cool as heck. how portable is that? i'd imagine video and audio drivers would be a problem if you wanted to go over to a buddy's house and just plug in. how cool would it be if someone had all the major video drivers pre-installed on the stick and the boot would just figure out which driver it needed to use!